Covalent dependence of octahedral rotations in orthorhombic perovskite oxides
Abstract
The compositional dependence of metal-oxygen BO6 octahedral distortions, including bond elongations and rotations, is frequently discussed in the ABO3 perovskite literature; structural distortions alleviate internal stresses driven by under- or over-coordinated bond environments. Here we identify the dependence of octahedral rotations from changes in metal-oxygen bond covalency in orthorhombic perovskites. Using density functional theory we formulate a covalency metric, which captures both the real and k-space interactions between the magnitude and sense, i.e., in-phase or out-of-phase, octahedral rotations, to explore the link between the ionic-covalent Fe–O bond and the interoctahedral Fe–O–Fe bond angles in Pbnm ferrates. Our survey finds that the covalency of the metal–oxygen bond is correlated with the rotation amplitude: We find the more covalent the Fe-O bond, the less distorted is the structure and the more important the long-range inter-octahedral (Fe-O-Fe bond angle) interactions. Finally, we show how to indirectly tune the B-O bond covalency by A-cation induced BO6 rotations independent of ionic size, facilitating design of targeted bonding interactions in complex perovskites.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Sep 19, 2014
- Source ID
- 10.1063/1.4895967
Entities
People
- Antonio Cammarata
- James M. Rondinelli
Organizations
- Czech Technical University in Prague
- Drexel University
- National Science Foundation
- Office of Naval Research